I work in production test. It is a constant battle with people who should know better trying to ship things that shouldn't be shipped.
I could absolutely imagine a scenario where someone comes up to an engineer says "we pass emissions in this scenario, but not these others" and then pushing, cajoling, even threatening that guy into "bending the rules" and "making things work" so they can start shipping. How much does the average car factory lose for each hour of downtime? Even more likely if the issue is a fundamental flaw that will cost millions to fix. All it takes a couple guys trying to be heroes or save their jobs.
Again, I'm not saying that's what I think happened, especially in light of how widespread the issue appears to be and how fast executives are jumping out with their golden chutes. But I do work in a similar industry in a similar capacity, depending on how the internal culture it would be easy for one or two people to make this happen.